1980 75 hp. Stinger Johnson J75TRLCSA Problems

Hello All

I have a 1980 75 hp. Stinger Johnson J75TRLCSA and am having power problems with it. In drive way with hose cup on, it runs fine, idles, powers up when advancing throtle. It also idles, powers up fine when in gear (forward & reverse). Now the problem! when you put boat in water, idles ok but when you put in gear it boggs out and dies, will not do anything under load. Pull boat out of water, motor idles, powers up fine when in gear (forward & reverse) again. Compression in all 3 cyls is good, I had carbs rebuilt 3 times. Changed out coil and power packs, still same problem. At a loss of ideas!

Mike
EDIT

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

Welcome to Iboats!
Are you running it with the portable fuel tanks or is it a built in tank?
Sounds like a fuel restriction problem.
Does the primer bulb pump up firm?

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

You are dropping at least one cylinder. Put a inductive timing light on it, one plug at a time under load, and see which one is not firing. If it is not fire, you may not be getting fuel.

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

Boat has built in 20 gal tank, was drained and has new filter inline. Also tried with hand carry tank and new fuel. Bulb pumps up firm.. Plugs all are firing fine, and changed them out with new ones.. Thanks for some clues..

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

Sounds to me like a fuel delivery problem.Most likely a dirty carb.
Classic symtoms.

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

run comp check .rebuild carbs ,do link and sink .but first check fire underload with timeing light,after comp check.

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

Benny1963 said:

run comp check .rebuild carbs ,do link and sink .but first check fire underload with timeing light,after comp check.

Click to expand...

Agree.

Comp. check first.

Secondly, you have a clogged carb. It must be disaasembled and cleaned. If not, you WILL score a cylinder.

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

All of the above. The timing light method will tell you if you've got spark under compression. Resistance for the spark is greater under compression than in the open air, so spark in the open may happen but it may dissipate under compression.

Might be able to use a squirt bottle of MIXED FUEL to localize a fuel delivery issue. Squirt in each carb and see if it picks up that cylinder. As noted, if it is a fuel issue and you continue to run it, you'll cook that cylinder for lack of lube...

- Scott

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

if its dropping a cylinder under load I'd compression and spark gap test it.
Autozone has the compression guage and spark gap tester. $29 and $12.

Set gap tester to 7/16th inch.
My money is on a bad coil or coil ground.

A timing light might still flash but you need to see the quality of the spark itself, went through that with mine.

Also check to see that the ignition starts to advance before the throttle starts to open. And order a factory manual to save shop fees.

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

You said you changed the coils and power pack.

Given the symptoms, a spark gap test will not do what an inductive timing light will do, which is to allow you to "read" the spark on each cylinder while the engine is running at various speeds;

In that way, you can determine if an ignition component is failing at speed.

BTW, you might want to check the wires from the powerpack to the amphenol for the ignition coils: 1 = Orange/blue; 2 = orange; and 3 = orange/green.

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

Hello all, well its been a while since I dug back into this engine, due to health issues. Any how I rebuilt the carbs again, and put in a better cleaner looking reed plate and leafs assembles, and new gaskets. Power pack was replaced last fall with new, and coil packs replaced with used. I have the service manual now, and wondering is a inductive timing light, the same as a regular auto timing light (which I have)? Well some results after install, motor cranked and started right up, and after 20 seconds went right to into idle and ran fine. I rag blocked each carb while running and there was noticeable RPM drop in bottom and middle carbs. Top carb had no effect on RPM!!! Checked all wiring and quick disconnects, changed top cylinder spark plug with new, same results.. Top carb is getting fuel, and even squited some in, no effect.. Thinking since I changed coil packs with used eBay ones, I ordered 3 new ones, should be here in a week. I really appreciate all your expertise in my problems..

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

You can have someone hand pump the tank while in water, that eliminates fuel pump problem. If you choke the motor and it dies instead of picking up and running, that eliminates carb problem. Most likely: electrical. How exactly did you check coils and power pack. To test power pack you would need (the equivalent of) a Mercotronic tester for that model (I have one from my racing days), and coils can break down and short to ground under load--are there any cracks in coil insulation? If so, then fill them with silicone seal. I have a 1958 Mercotronic testor that tests for coil leaks under load.

Mikey4x4 said:

Hello All

I have a 1980 75 hp. Stinger Johnson J75TRLCSA and am having power problems with it. In drive way with hose cup on, it runs fine, idles, powers up when advancing throtle. It also idles, powers up fine when in gear (forward & reverse). Now the problem! when you put boat in water, idles ok but when you put in gear it boggs out and dies, will not do anything under load. Pull boat out of water, motor idles, powers up fine when in gear (forward & reverse) again. Compression in all 3 cyls is good, I had carbs rebuilt 3 times. Changed out coil and power packs, still same problem. At a loss of ideas!

Mike
EDIT

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Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

Hi Sandhammaren05 , Was just running out of options, I have no tester for coils and power pack. Hope the problem is a bad coil, new coils should be arriving next week. Once I get engine working then I got to tackle the trailer rust, it's never ending!!!

Re: 1980 75 hp. Stinger Johnson J75TRLCSA Problems

Hello fellow boaters, well I got the new coils on engine and it runs like a raped ape, in the drive way anyway!! Got to get started now on the trailer repairs, then will launch and see what happens. Would like to thank you all again for all your help